Lighting control system

ABSTRACT

A lighting control system includes: a light fixture including a first light emitting device configured to emit light having a correlated color temperature in the range of ±100 K from a prescribed value, a second light emitting device configured to emit light having a correlated color temperature in the range of ±100 K from the prescribed value, and an emission controller configured to cause the light fixture to irradiate illumination light by controlling irradiation percentages of the light emitted from the first light emitting device and the light emitted from the second light emitting device; and an information processing apparatus communicably connected to the light fixture, the information processing apparatus comprising a dimming controller configured to change the irradiation percentages of the light emitted from the first light emitting device and the second light emitting device in accordance with a time of day by transmitting dimming instructions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2019-074278, filed on Apr. 9, 2019, and Japanese Patent Application No.2020-030910, filed on Feb. 26, 2020, the disclosures of which are herebyincorporated by reference in their entireties.

BACKGROUND

The present invention relates to a lighting control system and a lightfixture.

Lighting has become an essential element in buildings, such as offices,factories, commercial facilities, residences, and the like. In general,when a building with indoor spaces is constructed, lighting toilluminate the spaces is also installed.

Such indoor lighting, except for certain applications such as emergencylights, is usually provided for the purpose of creating a comfortablespace for people to work. For this reason, color rendering quality isused as one of the factors to determine the quality of indoor lighting.Japanese Patent Publication No. 2018-129492 discloses a light emittingdevice having high color rendering quality, i.e., an average ofrendering index (Ra) of 90 or higher.

In recent years, on the other hand, there has been a trend to giveimportance to considering the effect of lighting on the human body whencreating a work environment. For example, there is a certificationsystem known as WELL Certification (WELL Building Standards)administered by the International WELL Building Institute (IWBI). TheWELL Certification system evaluates office buildings or the like onmultiple features, such as air, water, nourishment, light, comfort andthe like, and certifies those buildings that meet the standards.

For example, the evaluation criteria related to light in the WELLCertification include, as requirements, visual lighting design,circadian lighting design, and electric light and solar glare control.Color rendering quality is not a requirement, but an item for addingpoints.

As such, there is a need for lighting for illuminating indoor spaceswhere people work to not only have good color rendering quality, butalso to address the effects on the human body.

SUMMARY

According to one embodiment, a lighting control system comprises: alight fixture comprising: a first light emitting device configured toemit light having a correlated color temperature in the range of ±100 Kfrom a prescribed value, a second light emitting device configured toemit light having a correlated color temperature in the range of ±100 Kfrom the prescribed value, and an emission controller configured tocause the light fixture to irradiate illumination light by controllingirradiation percentages of the light emitted from the first lightemitting device and the light emitted from the second light emittingdevice; and an information processing apparatus communicably connectedto the light fixture, the information processing apparatus comprising adimming controller configured to change the irradiation percentages ofthe light emitted from the first light emitting device and the lightemitted from the second light emitting device of the light fixture inaccordance with a time of day by transmitting dimming instructions. Theemission controller is configured to control the irradiation percentagesof the light emitted from the first light emitting device and the lightemitted from the second light emitting device based on the dimminginstructions such that a difference between a maximum melanopic ratio ofthe illumination light and a minimum melanopic ratio of the illuminationlight is 0.01 or higher in a time period during which the illuminationlight is irradiated.

According to another embodiment, a lighting control system comprises: alight fixture comprising: a first light emitting device configured toemit light having a correlated color temperature in the range of ±100 Kfrom a prescribed value, a second light emitting device configured toemit light having a correlated color temperature in the range of ±100 Kfrom the prescribed value, and an emission controller configured tocause the light fixture to irradiate illumination light by controllingirradiation percentages of the light emitted from the first lightemitting device and the light emitted from the second light emittingdevice; and an information processing apparatus communicably connectedto the light fixture, the information processing apparatus comprising adimming controller configured to change the irradiation percentages ofthe light emitted from the first light emitting device and the lightemitted from the second light emitting device of the light fixture inaccordance with a time of day by transmitting dimming instructions. Thefirst light emitting device is configured to emit the light in theregion of a CIE1931 color space chromaticity diagram defined by a firststraight line connecting a first point whose x, y coordinates are(0.280, 0.070) and a second point whose x, y coordinates are (0.280,0.500), a second straight line connecting the second point and a thirdpoint whose x, y coordinates are (0.013, 0.500), a pure purple locusextending from the first point towards smaller x values, and a spectrallocus extending from the third point towards smaller y values. Theemission controller is configured to control the irradiation percentagesof the light emitted from the first light emitting device and the lightemitted from the second light emitting device based on the dimminginstructions such that, at least in a correlated color temperature rangeof 3000K to 5000K, a difference between a maximum melanopic ratio of theillumination light and a minimum melanopic ratio of the illuminationlight is 0.40 or higher in a time period during which the illuminationlight is irradiated.

According to another embodiment, a lighting control system comprises: alight fixture comprising: a first light emitting device configured toemit light having a correlated color temperature in the range of ±100 Kfrom a prescribed value, a second light emitting device configured toemit light having a correlated color temperature in the range of ±100 Kfrom the prescribed value, and an emission controller configured tocause the light fixture to irradiate illumination light by controllingirradiation percentages of the light emitted from the first lightemitting device and the light emitted from the second light emittingdevice; and an information processing apparatus communicably connectedto the light fixture, the information processing apparatus comprising adimming controller configured to change the irradiation percentages ofthe light emitted from the first light emitting device and the lightemitted from the second light emitting device of the light fixture inaccordance with a time of day by transmitting dimming instructions. Thefirst light emitting device is configured to emit light in a region of aCIE1931 color space chromaticity diagram defined by a first straightline connecting a first point whose x, y coordinates are (0.280, 0.070)and a second point whose x, y coordinates are (0.280, 0.500), a secondstraight line connecting the second point and a third point whose x, ycoordinates are (0.013, 0.500), a pure purple locus extending from thefirst point towards smaller x values, and a spectral locus extendingfrom the third point towards smaller y values. The emission controlleris configured to control the irradiation percentages of the lightemitted from the first light emitting device and the light emitted fromthe second light emitting device based on the dimming instructions suchthat, at least in a correlated color temperature range of 2700K to6500K, a difference between a maximum melanopic ratio of theillumination light and a minimum melanopic ratio of the illuminationlight is 0.65 or higher in a time period during which the illuminationlight is irradiated.

Certain embodiments of the present disclosure can provide lightingbetter addressing the effects on the human body can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a circadian response curve and a visualsensitivity response curve.

FIG. 2 is a system configuration diagram of an example of the lightingcontrol system according to a first embodiment.

FIG. 3 is a schematic diagram of an example of the room structure in abuilding according to the first embodiment.

FIG. 4 is a block diagram explaining the hardware configuration of aninformation processing apparatus.

FIG. 5 is a block diagram explaining the software configuration of thelighting control apparatus according to the first embodiment.

FIG. 6 is a schematic diagram explaining a lighting apparatus accordingto the first embodiment.

FIG. 7 is a perspective view of a light fixture with a power adaptoraccording to the first embodiment.

FIG. 8 is a plan view explaining the emission face of a light fixtureaccording to the first embodiment.

FIG. 9 is a schematic diagram of a light emitting device according tothe first embodiment.

FIG. 10A shows examples of emission spectra of a light emitting deviceemployed in a light fixture according to the first embodiment.

FIG. 10B shows examples of emission spectra of a light emitting deviceemployed in a light fixture according to the first embodiment.

FIG. 10C shows examples of emission spectra of a light emitting deviceemployed in a light fixture according to the first embodiment.

FIG. 10D shows examples of emission spectra of a light emitting deviceemployed in a light fixture according to the first embodiment.

FIG. 10E shows examples of emission spectra of a light emitting deviceemployed in a light fixture according to the first embodiment.

FIG. 11 is a flowchart showing the flow of a lighting control executedby the lighting control system according to the first embodiment.

FIG. 12 is an example of the data structure for the dimming settinginformation according to the first embodiment.

FIG. 13A is a schematic diagram explaining one example of dimming rulesaccording to the first embodiment.

FIG. 13B is a schematic diagram explaining one example of dimming rulesaccording to the first embodiment.

FIG. 13C is a schematic diagram explaining one example of dimming rulesaccording to the first embodiment.

FIG. 13D is a schematic diagram explaining one example of dimming rulesaccording to the first embodiment.

FIG. 13E is a schematic diagram explaining one example of dimming rulesaccording to the first embodiment.

FIG. 14 is a a schematic diagram explaining a lighting apparatusaccording to the second embodiment.

FIG. 15 is a plan view explaining the emission face of a light fixtureaccording to the second embodiment.

FIG. 16 is a schematic diagram of a light emitting device according tothe second embodiment.

FIG. 17A is a schematic diagram of one example of a plurality of thelight emitting devices included in one package.

FIG. 17B is a schematic diagram of another example of a plurality of thelight emitting devices included in one package.

FIG. 17C is a schematic diagram of another example of a plurality of thelight emitting devices included in one package.

DETAILED DESCRIPTION

The effects of lighting on the human body will be explained first.

Taking the WELL Certification discussed in the background section forexample, a circadian-effective lighting design is required. Acircadian-effective lighting design means that the design addressescircadian rhythms.

The human circadian rhythm is longer than one day, i.e., about 25 hours,and unless adjusted to one day or 24 hours, it would be out of sync withthe 24-hour day. Light plays an important role as a factor tosynchronize the circadian rhythm with 24 hours. By being exposed tosunlight, human body's internal clock is adjusted to a 24-hour cycle.This allows humans to live in a natural daily rhythm, i.e., getting upin the morning and sleeping at night.

In other words, a human body is equipped with a synchronizing functionthat utilizes light in order to live in a 24-hour cycle. Specifically,there is an extremely small region of the brain in the hypothalamuscalled the supraoptic nucleus, which plays the role of setting theinternal clock for the circadian rhythm. The intrinsicallyphotosensitive retinal ganglion cells (hereinafter referred to asipRGCs) give light signals to the supraoptic nucleus.

It has been found that ipRGCs contain a photoreceptor protein known asmelanopsin, and that melanopsin is involved in photic entrainment ofcircadian rhythms. Melanopsin has wavelength-dependent absorptioncharacteristics with a peak absorbance in the vicinity of 480 nm to 490nm.

Moreover, melanopsin is said to be involved in secretion or restrictionof melatonin, which is a sleep inducing hormone. It is believed that thesecretion of melatonin is restrained, for example, by increasing thestimulus to ipRGCs. Normally, the peak secretion of melatonin in thebody occurs at night, and secretion of melatonin facilitates sleeping.Accordingly, the secretion of melatonin is restrained during the day.

In the process of WELL Certification discussed earlier, EquivalentMelanopic Lux (hereinafter referred to as EML) is introduced to evaluatewhether or not lighting has a circadian-effective design. The EML can beobtained using the formula (1) below.EML=Illuminance[lx]×Melanopic Ratio  (1)

The melanopic ratio (hereinafter referred to as MR) in formula (1) canbe obtained by the formula (2) below.

$\begin{matrix}{{{Melanopic}\mspace{14mu}{Ratio}} = {\frac{\overset{380}{\sum\limits_{730}}{{Light} \times {Circadian}}}{\overset{380}{\sum\limits_{730}}{{Light} \times {Visual}}} \times 1.218}} & (2)\end{matrix}$

The Light, the Circadian, and the Visual here refer to the spectraldistribution of the light produced by a light fixture, the circadianresponse based on the spectral sensitivity characteristics of melanopsinhaving a peak in the vicinity of 480 nm to 490 nm, and the visualsensitivity response, respectively. FIG. 1 shows a circadian responsecurve and a visual sensitivity response curve.

As is understood from the formula (1), two approaches are available toincrease the EML value: increase Illuminance or increase MR.Furthermore, MR apparently is more dependent on the circadian rhythmcharacteristics than Illuminance. Accordingly, it is preferable to focuson the MR value in addressing circadian rhythms. Based on the circadianresponses, the emission intensity in the wavelength range of about 470nm to about 490 nm is considered to particularly contribute to melatoninsecretion control.

Certain embodiments of the present invention will be explained belowwith reference to the accompanying drawings. The embodiments explainedbelow, however, are for giving shape to the technical ideas of thepresent invention, and are not intended to limit the present invention.In the explanation below, moreover, the same designations and referencenumerals show the same members or those having similar characteristics,for which the explanation will be omitted as appropriate. The sizes andpositional relationship of the members shown in the drawings might beexaggerated for clarity of explanation. The relationship between a colorname and chromaticity coordinates, the relationship between a wavelengthrange and a color name of monochromatic light, and the like are inaccordance with JIS Z8110.

First Embodiment

The lighting control system according to a first embodiment will beexplained. FIG. 2 is a system configuration diagram for the lightingcontrol system 100. A building 1 will be used as an example wherelighting control by the lighting control system 100 is executed.

The building 1, for example, is an office building in which theemployees of one or more companies work. An office building has multiplefloors and the example shown in FIG. 2 represents an office buildinghaving N floors. In the building 1, a reception is provided on the firstfloor, and one can go to any floor using an elevator.

On the second and higher floors, multiple rooms/spaces C are provided,and a company can rent and use a desired room 20. Each floor hasmultiple rooms 20. Room numbers, for example, are assigned asidentification information of each room 20. In the example shown in FIG.2, room numbers 201 and 202 are assigned to the two rooms 20 on thesecond floor, and N01 is assigned to one office 20 on the Nth floor.Using the typical room number format described above, it is common tostart a room number with the number that indicates the floor followed bya number to identify a specific room.

FIG. 3 is a diagram showing one example of a room 20 created in thebuilding 1. The room 20 forms a space surrounded primarily by a ceiling21, a floor 22, and walls 23. A door is provided in a portion of a wall23 for the access to the room, and windows are provided in severallocations to allow the outside air and light to enter the room. Theremay be a room without windows. Multiple lighting apparatuses 24 areinstalled on the ceiling 21 of the room 20. Moreover, air-conditioningequipment is disposed for adjusting the room temperature and humidity.

When a company uses a room, desks and chairs are further arranged in theroom. The people who work in the room 20 (employees) are subjected tothe illumination light provided by the lighting apparatuses 24 whilethey sit in the chairs and work at their desks. Accordingly, thelighting apparatuses 24 are arranged so as to provide illumination of atleast a certain illuminance that is appropriate for working. Forexample, in the case of performing general office work, illuminationlight is irradiated such that the illuminance on an upper surface of thedesk is at least 500 lx, more preferably at least 750 lx.

Such illuminance standards differ depending on the use of the building 1and the type of work performed there. For example, the standards mightdiffer among general office buildings, factories, schools, commercialfacilities, and the like. Furthermore, the standards might differdepending on the country. Japan has standards known as JIS Z9110, forexample.

Accordingly, “at least a certain illuminance” required of the lightingapparatus 24 installed on the ceiling 21 of the room 20 should besuitably determined based on the use of the building 1, the type of workperformed there, and the standards established in the country where thebuilding 1 is constructed. In this sense, the lighting control system100 is a system that can control irradiation of illumination lighthaving at least a certain illuminance in accordance with a workenvironment.

Furthermore, an office building is provided with a control room 10 forcontrolling the office building in addition to rooms 20 for rent tocompanies. In the control room 10, a system is installed for controllingbuilding equipment, such as an elevator, air-conditioning system,lighting, and the like. Moreover, the control room 10 is equipped with acontrol terminal 11 and a lighting control apparatus 12. Although thecontrol room 10 is located on the uppermost floor in the example shownin FIG. 2, it can be located on any given floor.

The broken lines in FIG. 2 show the connection between equipment forcommunication. In other words, the devices linked with the broken linesare communicably connected. The control terminal 11 and a plurality oflighting apparatuses 24 are communicably connected with the lightingcontrol apparatus 12. The lighting control apparatus 12 is communicablyconnected to the lighting apparatuses 24 subject to control, andcontrols the lighting apparatuses 24 through communication. For acommunicable connection, any known wired or wireless communication meanscan be used. The devices not linked by broken lines may be communicablyconnected. Moreover, it may be communicably connected to any deviceother than those shown in FIG. 2.

The control terminal 11 and the lighting control apparatus 12 can beconstructed with an information processing apparatus. For example, theinformation processing apparatus is a computer or a server. FIG. 4 is adiagram showing one example of the hardware configuration of aninformation processing apparatus. In the information processingapparatus, a CPU 70, a ROM 71, a RAM 72, a storage 73, a graphics I/F74, a data I/F 75, a communication I/F 76, and an input device 77 areconnected to a bus.

The storage 73 can be a nonvolatile memory medium that can store data.For example, a hard disk drive, flash memory, or the like can be used.The CPU 70 is a processor that executes processing in accordance with aprogram stored in the ROM 71 and the storage 73 by using the RAM 72 asthe working memory. The graphics I/F 74 is an interface that outputs thegenerated display control signals after being converted into signalsdisplayable by the system.

The data I/F 75 is an interface for inputting external data. Forexample, an interface utilizing an USB or the like can be applied. Thecommunication I/F 76 is an interface for communication with the networkusing a prescribed protocol. The input device 77 accepts a user inputand outputs a prescribed control signal.

FIG. 5 is a function block diagram explaining the information processing(function) executed by the lighting control apparatus 12. The functionrepresented by each function block is achieved, for example, when theCPU 70 executes a program. The lighting control apparatus 12 includes adimming control unit 13, a dimming setting registration unit 14, and adimming setting memory part 15.

The dimming control unit 13 is configured to manage one or more lightingapparatuses 24 arranged in each of rooms 20 in the building 1 andcontrols lighting by the lighting apparatus 24. For example, it controlslighting of the room 20 based on the settings related to dimming control(dimming settings).

The dimming setting registration unit 14 is configured to registerdimming settings. The dimming setting memory part 15 stores dimmingsetting information, which includes registered dimming settings. Forexample, when an office building administrator makes a registrationrequest to the lighting control apparatus 12 by inputting dimmingsettings using the control terminal 11, the dimming setting registrationunit 14 of the lighting control apparatus 12 registers the dimmingsettings in the dimming setting information in the dimming settingmemory part 15 in accordance with the registration request.

A lighting apparatus 24 includes a light fixture 30, a power sourceadaptor 50, and a dimming driver 60. FIG. 6 is a diagram showing oneexample of the lighting apparatus configuration and the connectionbetween the lighting apparatus 24 and an external device.

As shown in FIG. 6, in the lighting apparatus 24, the light fixture 30and the power supply adaptor 50 are connected, and the power supplyadaptor 50 and the dimming driver 60 are connected. The light fixture 30and the power supply adaptor 50 are connected by using an electricalwire, such as a DC harness. The power supply adaptor 50 and the dimmingdriver 60 are connected by using a communication wire such as acommunication cable. In other words, the light fixture 30 and the powersupply adaptor 50 are easily connected or disconnected by plugging orunplugging the electrical wire. Similarly, the power supply adaptor 50and the dimming driver 60 are easily connected or disconnected byplugging or unplugging the connection wire.

The power supply adaptor 50 is connected to the wiring provided behindthe ceiling of the building 1 and can receive a supply of power from anexternal power supply device. The dimming driver 60 is communicablyconnected to the lighting control apparatus 12 via a wired or wirelesscommunication means. The light fixture 30 and the power supply adaptor50 may be structured as an integral device. The power supply adaptor 50and the dimming driver 60 may be structured as an integral device.

The power supply adaptor 50 includes a power supply unit 51 thatsupplies power from an external power supply device to the lightfixtures 30. For example, the power supply unit 51 converts AC powerfrom an external power supply device into DC power to be supplied to thelight fixtures 30.

The dimming driver 60 includes a dimming controller 61 that adjusts thelight emitted by a light fixture 30. It also installs a driver programfor controlling the light from a light fixture 30. Accordingly, thedimming driver 60 is provided with an information processing mechanismfor executing a driver program. It includes, for example, a CPU, ROM,RAM, or the like. The dimming controller 61 receives from thecommunicably connected lighting control apparatus 12 a dimminginstruction, which includes the information for lighting control, andcontrols the light from a light fixture 30 based on the dimminginstruction.

The light fixture 30 includes a base plate 31, a substrate 32, aplurality of light emitting devices 36, an emission controller 35, acover 33, and a fixing member 34. The plurality of the light emittingdevices 36 include one or more first light emitting devices 37 and oneor more second light emitting devices 38. The light emitting device 36includes a light emitting element 39, a wavelength conversion member 40,and a molded part 42.

FIG. 7 is a perspective view of the light fixture 30 equipped with thepower supply adaptor 50 when viewed from the ceiling installation faceof the light fixture 30. FIG. 8 is a diagram showing the emission face(the face opposite the ceiling installation face) of the light fixture30. In FIG. 8, the light fixture 30 is shown without the cover 33. FIG.9 is a schematic cross-sectional view of a light emitting device 36included in the light fixture 30.

In the light fixture 30, the substrate 32 is attached to the base plate31. Multiple light emitting devices 36 are mounted on the substrate 32.The light emitting devices 36 are electrically connected via wiring, andpower is supplied to the light emitting devices 36 via the emissioncontroller 35 which controls the emission of the light emitting devices36.

Furthermore, the cover 33 is attached to the base plate 31 so as tosurround the light emitting devices 36 arranged on the substrate 32. Thefixing member 34 is provided on the ceiling installation surface, i.e.,the face of the base plate 31 opposite the face on which the lightemitting devices 36 are disposed. The light fixture 30 and the powersupply adaptor 50 are connected on the ceiling installation surfaceside. The power supply adaptor 50 is equipped with a power supplyterminal for connection with the external power supply device describedabove, and a dimming terminal for connection with the dimming driver 60.

In the light fixture 30, the first light emitting devices 37 and thesecond light emitting devices 38 are alternately arranged. In theexample shown in FIG. 8, multiple light emitting devices 36 are arrangedin rows and columns, where the first light emitting devices 37 and thesecond light emitting devices 38 are arranged in alternating rows (orcolumns). They may be alternated in different units other than rows orcolumns. For example, they may be alternated in units of a single ormultiple light emitting devices.

The light emitted from the first light emitting devices 37 has adifferent emission spectrum from that of the light emitted from thesecond light emitting devices 38. This can be achieved, for example, byvarying the types and/or the contents of the phosphors 41 contained inthe wavelength conversion member 40. This can alternatively be achievedby employing in the first light emitting devices 37 light emittingelements 39 that emit light having a different emission spectrum fromthat of the light emitted by light emitting elements 39 used in thesecond light emitting devices 38. Both the light emitting elements 39and the phosphors 41 may be varied.

In a light fixture 30, the emission controller 35 can individuallycontrol the light emission by the first light emitting devices 37 andthe light emission by the second light emitting devices 38. For example,it can allow only the first light emitting devices 37 or the secondlight emitting devices 38 to emit light. Moreover, it can adjust theemission intensity of each of the first light emitting devices 37 andthe second light emitting devices 38. The form of a light fixture 30 andthe form of a light emitting device 36 are not limited to those shown inthe drawings, and any known shape, structure, or construction can beutilized.

Here, the emission spectra of a light emitting devices 36 employed inthe lighting control system 100 according to the first embodiment willbe explained. A light fixture 30 can be produced by selecting for firstlight emitting devices 37 and second light emitting devices 38 lightemitting devices that emit light having different emission spectradescribed below as examples. The examples below are some of those thatcan be employed in the light fixture 30, and in applying the presentinvention, the light emitting devices do not have to be limited to thosedescribed below.

Light Emitting Device Example 1

The light emitting device 36 of example 1 includes a light emittingelement 39 having a peak emission wavelength in the range of 410 nm to490 nm, and a wavelength conversion member 40 containing a rare earthaluminate phosphor represented by the formula,(Y,Gd,Tb,Lu)₃(Al,Ga)₅O₁₂:Ce, and a silicon nitride phosphor representedby the formula, (Ca,Sr)AlSiN₃:Eu. FIG. 10A shows multiple emissionspectra achieved by varying the correlated color temperature values at achromaticity near the black body radiation locus by adjusting thecontents of the phosphors 41. The light emitting device 36 of example 1can achieve emission efficiency ranging from 180 lm/W to 210 lm/W and anaverage of rendering index ranging from 80, but under 90.

Here, a chromaticity near the black body radiation locus refers to lighthaving a color deviation, duv, of plus or minus 0.02 from the black bodyradiation locus measured in accordance with JIS Z8725. In thedescription herein, the multiple elements included in any phosphorcomposition formula using commas mean that at least one of theseelements is contained in the composition, and a combination of two ormore of the elements may be contained. In the description herein,moreover, what precedes the colon in any phosphor composition formularepresents the molar ratio of the elements making up the host crystal,and what follows the colon represents the activator.

Light Emitting Device Example 2

The light emitting device 36 of example 2 includes a light emittingelement 39 having a peak emission wavelength in the range of 410 nm to490 nm, and a wavelength conversion member 40 containing an alkalineearth metal aluminate phosphor represented by the formula,Sr₄Al₁₄O₂₅:Eu. FIG. 10B shows multiple emission spectra achieved byvarying the correlated color temperature values at a chromaticity nearthe black body radiation locus by adjusting the content of the phosphor41. The light emitting device 36 of Example 2 can achieve emissionefficiency ranging from 170 lm/W to 195 lm/W and an average of renderingindex ranging from 80 to 90.

Light Emitting Device Example 3

The light emitting device 36 of example 3 includes a light emittingelement 39 having a peak emission wavelength in the range of 410 nm to490 nm, and a wavelength conversion member 40 containing a silicatephosphor represented by the formula, (Ca,Sr,Ba)₈MgSi₄O₁₆(F,Cl,Br)₂:Eu.FIG. 10C shows multiple emission spectra achieved by varying thecorrelated color temperature values at a chromaticity near the blackbody radiation locus by adjusting the content of the phosphor 41. Thelight emitting device 36 of Example 3 can achieve emission efficiencyranging from 155 lm/W to 185 lm/W and an average of rendering indexranging from 90, but under 95.

Light Emitting Device Example 4

The light emitting device 36 of example 4 includes a light emittingelement 39 having a peak emission wavelength in the range of 410 nm to490 nm, and a wavelength conversion member 40 containing an alkalineearth phosphate phosphor represented by the formula,(Ca,Sr,Ba)₅(PO₄)₃(Cl,Br):Eu and a fluorogermanate phosphor representedby the formula 3.5MgO.0.5MgF₂.GeO₂:Mn. FIG. 10D shows multiple emissionspectra achieved by varying the correlated color temperature values at achromaticity near the black body radiation locus by adjusting thecontents of the phosphors 41. The light emitting device 36 of Example 4can achieve emission efficiency ranging from 115 lm/W to 140 lm/W and anaverage of rendering index ranging from 95, but under 100.

Light Emitting Device Example 5

The light emitting device 36 of example 5 includes a light emittingelement 39 having a peak emission wavelength in the range of 410 nm to490 nm, and a wavelength conversion member 40 containing an alkalineearth metal aluminate phosphor represented by the formula,Sr₄Al₁₄O₂₅:Eu. FIG. 10E shows the emission spectrum of the lightemitting device 36 of example 5. The light emitting device 36 of example5 is a light emitting device with enhanced light intensity in the 470 nmto 490 nm range of the wavelength that shows a circadian-effectiveemission spectrum.

The light emitting device 36 emits light in the region in the CIE1931color space chromaticity diagram defined by the first straight lineconnecting the first point whose x, y coordinates are (0.280, 0.070) andthe second point whose x, y coordinates are (0.280, 0.500), the secondstraight line connecting the second point and the third point whose x, ycoordinates are (0.013, 0.500), the pure purple locus extending from thefirst point towards smaller x values, and the spectral locus extendingfrom the third point in towards smaller y values. Since this light is ofthe chromaticity distant from the black body radiation locus,illumination light is created by color toning with other light emittingdevices.

The light emitting device 36 of example 5 has an MR value of at least2.0. The percentage of the light intensity in the 470 nm to 490 nm rangerelative to the light intensity across the entire emission spectrum isat least 15%. It can achieve an emission efficiency ranging from 115lm/W to 140 lm/W.

The emission spectral characteristics of these light emitting deviceexamples 1 to 5 can be identified based on FIGS. 10A to 10E. Forexample, the wavelength range having a peak wavelength, the full widthat half maximum, and the like can be identified using the drawings.

Lighting Control

Lighting control performed by the lighting control system 100 will beexplained next. FIG. 11 is a flowchart showing the flow of lightingcontrol performed by the lighting control system 100. Each step in thesequence will be described below.

In step S1, the light switch is turned on. The switch is used by, forexample, an employee of a company who first arrives at the room 20 onthat day. Alternatively, a computer may be allowed to automatically turnthe switch on by remote control. For example, in the case in which theentrance gates on the first floor of the office building requireauthorization using an IC card such as an employee ID card, it may beadapted such that an authorization of an employee using the IC cardturns on the light switch for the office space of the company of theemployee.

In step S2, the lighting control apparatus 12 receives a lightingrequest, which is a signal that requests that the lights be turned on.The lighting request includes light specifying information thatspecifies one or more target lighting apparatuses 24 subject to ON/OFFcontrol by the light switch. For example, room numbers can be used forthe light specifying information. In this case, the lighting apparatus24 will be controlled per room. In the case of a large room 20, the room20 may be divided into two or more areas to be used as the units ofcontrol.

In step S3, the dimming control unit 13 of the lighting controlapparatus 12 acquires dimming settings from the dimming settinginformation stored in the dimming setting memory part 15. Based on thelight specifying information included in the received lighting requestand the dimming setting information stored in the dimming setting memorypart 15, the dimming control unit 13 acquires dimming settingsassociated with the light specifying information.

FIG. 12 is a diagram showing one example of the data structure of thedimming setting information stored in the dimming setting memory part15. The dimming setting information in this example is tenantinformation 16 set in units of companies that rent rooms 20, in otherwords, in units of tenants occupying one or multiple rooms 20 of thebuilding 1.

The tenant information 16 includes a tenant identification code, floor,room, and basic business hours in accordance with each tenant areregistered. The information item “tenant identification code” is theinformation used to identify a company renting a room 20, i.e., a tenantunder a rental agreement. The floor on which the room 20 rented by thetenant is registered in the information item “floor.” The room numberassigned to the room 20 rented by the tenant is registered in theinformation item “room.” That is, light specifying information isregistered in the tenant information 16.

A time period selected by the tenant is registered in the informationitem “the basic business hours.” Each tenant can suitably determinethis, but the start time to the end time based on the type of businessis typically registered as basic business hours. It is generally assumedthat the start time is set between 07:00 and 10:30, and the end time isset between 16:00 and 19:00.

As shown in FIG. 12, moreover, a company renting two or more rooms canregister different basic business hours depending on the room. In thecase in which a company turns off the lights during a lunch break, thecompany can register the lunch hour. The dimming control unit 13 of thelighting control apparatus 12 acquires from the tenant information 16the dimming settings associated with the light specifying informationincluded in the lighting request.

FIG. 13A to FIG. 13E are diagrams explaining examples of the dimmingsetting information stored in the dimming setting memory part 15. Thedimming setting information in these examples represents dimming ruleinformation 17 that specifies how lighting is controlled in a dailycycle.

The dimming rule information 17 defines, for example, the degree ofcircadian characteristics in accordance with the time or time periodsuch that the circadian characteristics change in accordance with time.In the case of performing color toning, the correlated colortemperatures may be specified in accordance with time. FIG. 13A to FIG.13D show dimming rule examples specifying circadian characteristics inaccordance with time, and FIG. 13E shows a dimming rule examplespecifying correlated color temperatures in accordance with time.

In a light fixture 30, changing the irradiation percentages of the lightfrom the first light emitting devices 37 and the light from the secondlight emitting devices 38 can change the circadian characteristics orthe correlated color temperatures of the lighting provided by a lightingapparatus 24. In other words, the dimming rule information defines therules for changing the irradiation percentages of the light from thefirst light emitting devices 37 and the light from the second lightemitting devices 38 of a light fixture 30 in accordance of the timeperiods in one day.

In the example shown in FIG. 13A (Dimming Rules 1), from 00:00 to 06:00the circadian characteristic value is the minimum value of the day,which changes to the maximum value at 06:00. Subsequently, the maximumvalue is maintained until 15:30, and from 15:30 to the end time of thebasic business hours, the circadian characteristic value decreases withthe passage of time. It becomes the minimum value past the end timeuntil 24:00.

In other words, it is specified by the Dimming Rules 1 that thecircadian characteristic value is to increase at the prescribed timedetermined by the administrator of the building 1 (06:00). It is alsospecified that the circadian characteristic value is to begin decreasingat the prescribed time determined by the administrator of the building 1(15:30). Moreover, it is specified that the circadian characteristicvalue begins to gradually decrease at the prescribed time determined bythe administrator of the building 1 (15:30) until the prescribed timedetermined by a tenant (the end time of the basic business hours).

In the example shown in FIG. 13B (Dimming Rules 2), from 00:00 to onehour before the start time of the basic business hours the circadiancharacteristic value is the minimum value of the day, which changes tothe maximum value at one hour before the start time. Subsequently, themaximum value is maintained until 15:30, and from 15:30 to 18:00 thecircadian characteristic value decreases with the passage of time. Itbecomes the minimum value past 18:00 until 24:00.

In other words, it is specified by the Dimming Rules 2 that thecircadian characteristic value is to increase at the prescribed timedetermined by a tenant (the start time of the basic business hours). Itis also specified that the circadian characteristic value is to begindecreasing at a prescribed time determined by the administrator of thebuilding 1 (15:30). Moreover, it is specified that the circadiancharacteristic value is to gradually decrease during the prescribed timeperiod determined by the administrator of the building 1 (from 15:30 to18:00). Moreover, it is specified that the time to increase thecircadian characteristic value is decided based on the prescribed timedetermined (the start time of the basic business hours) and the presetconditions (one hour before the start time) by a tenant.

In the example shown in FIG. 13C (Dimming Rules 3), from 00:00 to 06:00the circadian characteristic value is the minimum value of the day, andfrom 06:00 to the start time of the basic business hours the circadiancharacteristic value increases with the passage of time. Subsequently,the maximum value is maintained from the start time to the end time,which changes to the minimum value at the end time. Past the end time,it is maintained at the minimum value until 24:00.

In other words, it is specified by the Dimming Rules 3 that thecircadian characteristic value is to begin increasing at the prescribedtime determined by the administrator of the building 1 (06:00). It isalso specified that the circadian characteristic value begins decreasingat the prescribed time determined by a tenant (the end time of the basicbusiness hours). Furthermore, it is specified that the circadiancharacteristic value begins gradually increasing at the prescribed timedetermined by the administrator of the building 1 (06:00) until theprescribed time determined by a tenant (the start time of the basicbusiness hours).

In the example shown in FIG. 13D (Dimming Rules 4), from 00:00 to thesunrise time (sunrise time) the circadian characteristic value is theminimum value of the day, and from the sunrise time to the start time ofthe basic business hours the circadian characteristic value increaseswith the passage of time. Subsequently, the maximum value is maintaineduntil 15:30, and from 15:30 to the end time of the basic business hoursthe circadian characteristic value is reduced with the passage of time.The circadian characteristic value does not reach the minimum value atthe end time, instead the circadian characteristic value continues todecrease past the end time. It becomes the minimum value at 20:00, whichis maintained until 24:00.

In other words, it is specified by the Dimming Rules 4 that the time toincrease the circadian characteristic value is decided based on thenatural environmental information (sunrise time). A sunrise time can beset based on the statistical data in the region where the lightingcontrol system 100 is installed. Dimming rules may be set to reduce thecircadian characteristic value in line with sunset based on a sunsettime. Alternatively, dimming rules may be set such that the circadiancharacteristic value becomes minimum from sunset to sunrise.

It is specified by the Dimming Rules 4 that the circadian characteristicvalue begins decreasing at a prescribed time determined by the tenant(the end time of the basic business hours) to a prescribed percentage ofthe maximum value (e.g., 50%) with the passage of time. It is furtherspecified that subsequently the circadian characteristic value decreaseswith the passage of time until a prescribed time determined by theadministrator of the building 1 (20:00).

In the example shown in FIG. 13E (Dimming Rules 5), from 00:00 to 06:00the correlated color temperature is the minimum value of the day, andfrom 06:00 to the start time of the basic business hours the correlatedcolor temperature increases with the passage of time. Subsequently, themaximum value is maintained from the start time to 15:30, and from 15:30to the end time of the basic business hours the correlated colortemperature decreases with the passage of time. Past the end time, theminimum value is maintained until 24:00.

In other words, it is specified by the Dimming Rules 5 that thecorrelated color temperature is to begin increasing at a prescribed timedetermined by the administrator of the building 1 (06:00). It is alsospecified that the correlated color temperature is to begin decreasingat a prescribed time determined by the administrator of the building 1(15:30). It is specified that the correlated color temperature isgradually increased or reduced.

As described above, dimming rules define how the circadiancharacteristic value of the light produced by the lighting apparatuses24 changes during the day. The circadian characteristic value can bechanged by changing the irradiation percentages of the light from thefirst light emitting devices 37 and the light from the second lightemitting devices 38 of a light fixture 30.

It is preferable for the dimming rules to specify that the melanopicratio of the illumination light at 10:00 is higher than the circadiancharacteristic value of the illumination light at 17:00. It ispreferable to specify that the difference between the maximum andminimum circadian characteristic values from 10:00 to 12:00 is smallerthan the difference between the maximum and minimum circadiancharacteristic values from 14:00 to 18:00. It is preferable to specifythat the average circadian characteristic value from 10:00 to 12:00 ishigher than the average circadian characteristic value from 16:00 to18:00.

Dimming rules are not limited to those described in these examples, andcan be established by combining the elements disclosed in the examples.Furthermore, dimming rules may be created by incorporating elementsother than those disclosed in the example. Dimming rules may be createdfor lunch breaks, for example.

Such dimming rules are designed to address the effects on the humanbody. Although the details will be described later, by appropriatelyselecting first light emitting devices 37 and second light emittingdevices 38, lighting control addressing the effects on the human bodycan be performed even by the Dimming Rules 5, which specify correlatedcolor temperatures. In the lighting control system 100, dimming rulesaddress daily rhythms of humans of getting up in the morning andsleeping at night by establishing modes of lighting control such thatthe circadian characteristic value is high during active hours such asthe morning and the afternoon, and the circadian characteristic value islower in the evening and the night than the daytime. Creating dimmingrules matching the business type of a tenant can facilitate healthydaily rhythms while increasing the intellectual productivity ofemployees during business hours.

The dimming control unit 13 of the lighting control apparatus 12acquires such dimming rule information 17 from the dimming settinginformation stored in the dimming setting memory part 15. The dimmingsetting memory part 15 can simply store at least one set of registereddimming rules in the dimming rule information. In the case of one set ofdimming rules, the rules will be uniformly applied to tenants.

A plural sets of dimming rules may be stored to allow a tenant to selectapplied dimming rules. It may alternatively be adapted to registercustomized dimming rules considering the business type of a tenant. Inthe case of applying dimming rules in accordance with tenants, forexample, information specifying the dimming rules to be applied to eachtenant is registered in the tenant information.

In step S4, the dimming control unit 13 of the lighting controlapparatus 12 determines the dimming level at the current time based onthe dimming setting information acquired. For example, based on thetenant information and the dimming rule information, it specifies thedimming level corresponding to the circadian characteristic or thecorrelated color temperature at the current time, and determines theirradiation percentage of the light from the first light emittingdevices 37 and the irradiation percentage of the light from the secondlight emitting devices 38.

The irradiation percentages of the first light emitting devices 37 andthe second light emitting devices 38 may be determined at the dimmingdriver 60. In other words, the lighting control apparatus 12 specifiesthe circadian characteristic or correlated color temperature value(dimming level) and sends the value (dimming level) to the dimmingdriver 60. Then the irradiation percentages can be determined at thedimming driver 60 in response to receiving the dimming level. Thecorrespondence between circadian characteristic values and irradiationpercentages of the light emitting devices 36 is managed as thecharacteristic data of the light fixtures 30 by the lighting controlsystem 100 (the lighting control apparatus 12 or the dimming driver 60).

Here, in the case in which the lighting control system 100 is used by acompany in a building 1 such as an office building, illuminance of acertain value or higher suited for the work environment is maintainedwhile the lights are on. In other words, when changing the circadiancharacteristics, the lighting control is performed so as not toexcessively reduce the illuminance, which can impair employees' abilityto work. In a general office building, light fixtures 30 irradiateillumination light such that the desktop illuminance is at least 500 lx,for example.

Furthermore, at least in the basic employee working hours, while thelights are on, the illuminance is controlled to be at a certain level orhigher in accordance with the work environment. The basic employeeworking hours, for example, are from the start time or 09:00 to the endtime or 18:00, excluding lunch breaks, without limiting the workinghours. For example, countries that have daylight savings time might haveearlier working hours.

In step S5, the dimming control unit 13 of the lighting controlapparatus 12 transmits dimming instructions to one or more lightingapparatuses 24 such that lighting by the lighting apparatus 24 iscontrolled to the decided dimming level. In the configuration shown inFIG. 6, the lighting control apparatus 12 transmits dimming instructionsto the dimming driver 60 communicably connected thereto. Subsequently,the lighting control apparatus 12 periodically determines dimming levelsand transmits dimming instructions until it receives a request to turnoff the lights after the light switch is turned off After receiving arequest to turn off the lights, it transmits a turn off instruction toone or more lighting apparatuses 24.

In step S6, a lighting apparatus 24 that received a dimming instructionirradiates illumination light by controlling the irradiation percentagesof the light from the first light emitting devices 37 and the light fromthe second light emitting devices 38 of the light fixture 30 inaccordance with the received dimming instruction. The lights are now on.In the configuration shown in FIG. 6, the dimming controller 61 of thedimming driver 60 controls the emission controller 35 of a light fixture30, and the emission controller 35 allows the first light emittingdevices 37 and the second light emitting devices 38 to emit light atappropriate irradiation percentages in accordance with the control.

The dimming driver 60 may be adapted to store one or more dimming rulesapplicable to the light fixtures 30 subject to dimming control andexecute the processing of steps S2 to S6. In this case, the lightingcontrol apparatus 12 transmits dimming settings to an applicable dimmingdriver 60 when registration or updating of dimming setting informationoccurs in connection with a newly entered or renewed rental agreement,and the dimming driver 60 stores the dimming settings received. In thecase in which dimming rules are based on the start time and the endtime, the lighting control apparatus 12 transmits dimming settings,which include dimming rules and condition parameters (start time or endtime).

As described above, the lighting control system 100 performs dimming inaccordance with the hours based on the dimming rules while lights areon.

Next, various cases will be explained in which light emitting devicesfor use as the first light emitting devices 37 and the second lightemitting devices 38 in the lighting control system 100 are selected fromamong the light emitting device examples 1 to 5 and subjected to dimmingcontrol performed based on the dimming rules discussed above. The casesin which color toning control is performed and the cases in which thecolor toning control is not performed will be separately explained.

In cases of not performing color toning control, light emitting devicesthat emit light having the same correlated color temperature can beemployed for the first light emitting devices 37 and the second lightemitting devices 38. Accordingly, in these cases the light emittingdevice example 5 is not employed for any of the first light emittingdevices 37 and the second light emitting devices 38. For example, in anoffice building, a light fixture 30 emitting daylight color or neutralwhite light is often employed. In terms of correlated color temperaturesin the CIE1931 color space chromaticity diagram, a light emitting deviceemitting light in the 3000K to 7000K range is often employed.

The two light emitting devices having the same correlated colortemperature here are not limited to those cases where they have strictlythe same correlated color temperature value. This can have a correlatedcolor temperature range recognized as the same color range in the fieldof lighting, for example, both having daylight colors, neutral whitecolors, or incandescent lamp colors. Moreover, correlated colortemperatures in the range of 5000K to 6000K, from 3500K to 4500K, orfrom 2000K to 3000K, may be considered as the same correlated colortemperatures. However, the correlated color temperature differencebetween the light from a first light emitting device 37 and the lightfrom a second light emitting device 38 is preferably ±500K at most, morepreferably ±100K at most.

Furthermore, the allowable range of difference for higher correlatedcolor temperatures may be greater than the allowable range of differencefor lower correlated color temperatures. For example, in the case ofaligning the two light emitting devices at a correlated colortemperature higher than 6500K, the difference is preferably within±500K. Accordingly, in the case of aligning at 6500K, the variationranging from 7000K to 6000K is allowed as the same correlated colortemperature. In the case of aligning at any temperature in the 5000K to5750K range, the variation preferably falls within ±250K. In the case ofaligning at any temperature in the 3400K to 4600K range, the variationpreferably falls within ±150K. In the case of aligning at anytemperatures in the 2700K to 3150K range, the variation preferably fallswithin ±100K.

Table 1 summarizes the circadian characteristics in the cases ofselecting for the first light emitting devices 37 and the second lightemitting devices 38 various light emitting devices from examples 1 to 4and performing dimming control based on dimming rules. Here, for thecircadian characteristics, MR (melanopic ratio) and the percentage ofthe light intensity in the 470 nm to 490 nm range relative to the lightintensity of the entire emission spectrum, were obtained. They arerespectively labeled as Circadian Characteristic 1 and CircadianCharacteristic 2 in the table.

TABLE 1 First Light Correlated Color Second Light Correlated ColorCircadian Circadian Emitting Temperature/ Emitting Temperature/Characteristic 1 Characteristic 2 Examples Device Chromaticity DeviceChromaticity Highest Lowest Highest Lowest Example 1-1 Example 3 3000 KExample 1 3000 K 0.589 0.471 2.63% 1.41% Example 1-2 Example 2 3000 KExample 4 3000 K 0.572 0.561 3.77% 2.56% Example 1-3 Example 2 3000 KExample 1 3000 K 0.572 0.471 3.77% 1.41% Example 1-4 Example 3 3000 KExample 4 3000 K 0.589 0.561 2.63% 2.56% Example 2-1 Example 4 5000 KExample 1 5000 K 0 934 0.799 7.03% 3.63% Example 2-2 Example 2 5000 KExample 3 5000 K 0.886 0.852 5.37% 3.87% Example 2-3 Example 2 5000 KExample 1 5000 K 0.886 0.799 5.37% 3.63% Example 2-4 Example 3 5000 KExample 1 5000 K 0.852 0.799 3.87% 3.63% Example 3-1 Example 4 6500 KExample 1 6500 K 1.116 0.948 8.66% 3.92% Example 3-2 Example 2 6500 KExample 3 6500 K 1.046 1.015 6.85% 4.76% Example 3-3 Example 2 6500 KExample 1 6500 K 1.046 0.948 6.85% 3.92% Example 3-4 Example 3 6500 KExample 1 6500 K 1.015 0 948 4.76% 3.92%

By irradiating illumination light while allowing only the light emittingdevices having a higher circadian characteristic value between the firstlight emitting devices 37 and the second light emitting devices 38 toemit light, dimming control that maximizes circadian characteristics canbe performed. On the other hand, by irradiating illumination light whileallowing only the light emitting devices having a lower circadiancharacteristic value between the first light emitting devices 37 and thesecond light emitting devices 38 to emit light, dimming control thatminimizes circadian characteristics can be performed. In Table 1, lightemitting devices having higher circadian characteristic values areentered as the first light emitting devices 37 and light emittingdevices having lower circadian characteristic values are entered as thesecond light emitting devices 38.

The control for achieving the maximum or minimum circadiancharacteristic value does not necessarily have to take the form ofallowing only the first light emitting devices 37 or the second lightemitting devices 38 to emit light. By adjusting the emission percentagesof the first light emitting devices 37 and the second light emittingdevices 38, the maximum and the minimum circadian characteristic valuesspecified by the dimming rules can be achieved.

As is understood from Table 1, in the case of any lighting controlsystem 100 controlling lighting by the lighting apparatuses 24 at thesame correlated color temperature, a difference of 0.010 or greater canbe achieved between the maximum and the minimum values of the circadiancharacteristic 1 in the daily cycle. Furthermore, the difference can be0.165 or greater.

A difference of 0.05% or greater can be achieved between the maximum andthe minimum values of the circadian characteristic 2 in the daily cycle.Furthermore, the difference can be 4.70% or greater.

The control ranges for the circadian characteristic 1 and the circadiancharacteristic 2 for other correlated color temperatures can similarlybe derived from what is disclosed in Table 1. Furthermore, comprehensivecontrols can be performed by combining Table 1 with the emissionefficiency and the average color rendering indices of the light emittingdevice examples 1 to 4.

For example, Examples 1-3, 2-3, and 3-3 in Table 1 show the results ofselecting from among the light emitting device examples 1-4 two lightemitting devices having good emission efficiency. The results show thatthe difference between the maximum and the minimum values of thecircadian characteristic 1 can be 0.085 or greater while maintainingemission efficiency of 170 lm/W or higher. Furthermore, the differencecan be 0.100 or greater.

In the cases where the correlated color temperatures for the first lightemitting devices 37 and the second light emitting devices 38 are 5000Kand 6500K, the examples having the largest difference between themaximum and minimum values of the circadian characteristic 1 and theexamples having the largest difference between the maximum and theminimum values of the circadian characteristic 2 are common.Specifically, Example 2-1 and Example 3-1 are the examples having thelargest differences in both characteristic values.

Circadian characteristic 1 is an assessed value corresponding to acircadian response, and circadian characteristic 2 is an assessed valuecorresponding to a melanopic peak wavelength of 470 nm to 490 nm. As isunderstood from the circadian responses shown in FIG. 1, circadiancharacteristic 1 is affected by the emission spectra outside the 470 nmto 490 nm wavelength range.

By using a light fixture 30 having a large difference in circadiancharacteristic 1 and a large difference in circadian characteristic 2, alighting control system 100 with good circadian responses and goodmelatonin secretion controls can be achieved.

In the case of performing color toning controls, light emitting devicesthat emit light having different correlated color temperatures can beused for the first light emitting devices 37 and the second lightemitting deices 38. Toning ranges, for example, can be from 2700K to6500K, from 3000K to 5000K, or the like. In other words, a light fixture30 that can be toned to range from incandescent lamp color to daylightor neutral white color is often employed.

In the case of performing color toning in sync with a circadian rhythm,a light emitting device having a higher circadian characteristic valueis used for a first light emitting device 37 and a light emitting devicehaving a lower circadian characteristic value is used for a second lightemitting device 38 assuming that the first light emitting device 37 hasa higher correlated color temperature and the second light emittingdevice 38 has a lower correlated color temperature. This is becausedaylight or neutral white light having a high correlated colortemperature is irradiated during the day, and incandescent light havinga low correlated color temperature is irradiated in the morning and theevening. The manner in which color toning is performed is not limited tothis, but performing color toning against a natural rhythm mightadversely affect the human body.

Table 2 summarizes the circadian characteristics in the cases ofselecting for the first light emitting devices 37 and the second lightemitting devices 38 different light emitting devices from among thelight emitting device examples 1 to 5, and performing dimming controlsbased on the dimming rules. Because circadian characteristic values canchange even if the same light emitting devices are used when subjectedto color toning controls, the results obtained when using the same lightemitting devices for the first light emitting devices 37 and the secondlight emitting devices 38 are listed as comparative examples.

TABLE 2 Correlated Correlated Examples/ First Light Color Second LightColor Circadian Circadian Comparative Emitting Temperature/ EmittingTemperature/ Toning Characteristic 1 Characteristic 2 Examples DeviceChromaticity Device Chromaticity Range Highest Lowest Highest LowestComparative Example 4 6500 K Example 4 2700 K 2700 K- 1.116 0.493 8.66%2.16% Example 1 6500 K Example 4-1 Example 4 6500 K Example 1 2700 K2700 K- 1.116 0.439 8.66% 1.60% 6500 K Example 4-2 Example 5 x = 0.149Example 1 2700 K 2700 K- 1.240 0.439 10.34% 1.60% y = 0.234 6500 KComparative Example 4 5000 K Example 4 3000 K 3000 K- 0.934 0.561 7.03%2.56% Example 2 5000 K Example 5-1 Example 2 5000 K Example 1 3000 K3000 K- 0.886 0.471 5.37% 1.41% 5000 K Example 5-2 Example 4 5000 KExample 1 3000 K 3000 K- 0.934 0.471 7.03% 1.41% 5000 K Example 5-3Example 5 x = 0.149 Example 1 3000 K 3000 K- 0.982 0.471 7.45% 1.41% y =0.234 5000 K Example 5-4 Example 2 6500 K Example 1 2700 K 3000 K- 0.8790.516 5.49% 2.31% 5000 K Example 5-5 Example 4 6500 K Example 1 2700 K3000 K- 0.937 0.521 7.15% 2.69% 5000 K Example 5-6 Example 5 x = 0.149Example 1 2700 K 3000 K- 1.020 0.539 8.25% 2.88% y = 0.234 5000 K

In a lighting control system 100 that controls color toning, thecircadian characteristics became maximum at the highest of the colortoning range, and the circadian characteristics became minimum at thelowest of the color toning range. In the examples, the circadiancharacteristic 1 and the circadian characteristic 2 of the lightemitting device sample 5 are 2.843 and 21.32%, respectively.

As is understood from Table 2, in the case of a lighting control system100 that controls color toning of the light from the lightingapparatuses 24, the difference between the maximum and the minimumvalues of the circadian characteristic 1 in the daily cycle can be 0.65or greater in the color toning range of 2700K to 6500K. Furthermore, thedifference can be 0.80 or greater.

Furthermore, the difference between the maximum and the minimum valuesof the circadian characteristic 1 in the daily cycle can be 0.40 orgreater in the color toning range of 3000K to 5000K. Furthermore, thedifference can be 0.50 or greater. As such, the controllable range forthe circadian characteristic 1 is larger when color toning is performedas compared to performing controls using the same color.

The difference between the maximum and the minimum values of thecircadian characteristic 2 in the daily cycle can be 6.50% or greater inthe color toning range of 2700K to 6500K. Furthermore, the differencecan be 7.00% or greater.

The difference between the maximum and the minimum values of thecircadian characteristic 2 in the daily cycle can be 4.50% or greater inthe color toning range of 3000K to 5000K. Furthermore, the differencecan be 5.00% or greater.

As is understood from Table 2, the lighting control system 100 cancontrol color toning in the range of 2700K to 6500K using a lightingapparatus C that includes first light emitting devices having acircadian characteristic 1 value of 1.13 or higher and second lightemitting devices having a circadian characteristic 1 value of 0.48 orlower. Furthermore, it can control color toning in the range of 3000K to5000K by using a lighting apparatus C that includes first light emittingdevices having a circadian characteristic 1 value of 0.95 or higher andsecond light emitting devices having a circadian characteristic 1 valueof 0.55 or lower.

Examples 5-1 to 5-3 and Examples 5-4 to 5-6 are two groups of examplessubjected to the same color toning range, but the correlated colortemperature of the light from the first light emitting devices 37 andthe correlated color temperature of the light from the second lightemitting devices 38 are different (except for the light emitting deviceexample 5). The results in Table 2 show that the values differ even ifthe color toning range is the same.

Even when color toning in the range of 3000K to 5000K is performed byusing 2700K first light emitting devices 37 and 6500K second lightemitting devices 38, the difference between the maximum and the minimumvalues of the circadian characteristic 1 can be 0.40 or greater.Furthermore, the difference can be 0.45 or greater.

It is observed that when employing the same combination of the lightemitting device examples in two lighting apparatuses, the lightingapparatus using the light emitting devices that emitting light having acorrelated color temperature close to the color toning range tends tofurther reduce the minimum values of the circadian characteristics, andthe lighting apparatus using the light emitting devices that emit lighthaving a correlated color temperature distant from the color toningrange further increases the maximum value. Moreover, it is understoodthat the lighting apparatus having good circadian characteristics can beproduced with light emitting devices that emit light having a correlatedcolor temperature that is not close to the color toning range.

In the case of performing color toning in the 3000K to 5000K range, forexample, light emitting devices that emit light having a correlatedcolor temperature in the 5000K to 8000K range can be employed for thefirst light emitting devices 37. For the second light emitting devices38, light emitting devices having a correlated color temperature in the1500K to 3000K range can be employed.

In the case of performing color toning in the 2700K to 6500K range, forexample, light emitting devices that emit light having a correlatedcolor temperature in the 6500K to 8000K range can be employed for thefirst light emitting devices 37. For the second light emitting devices38, light emitting devices that emit light having a correlated colortemperature in the 1500K to 2700K range can be used.

When performing color toning, for example, in lieu of light emittingdevices that emit light having a correlated color temperature of 8000Kat most, those that emit light in the region of the CIE1931 color spacechromaticity diagram defined by the first straight line connecting thefirst point whose x, y coordinates are (0.280, 0.070) and the secondpoint whose x, y coordinates are (0.280, 0.500), the second straightline connecting the second point and the third point whose x, ycoordinates are (0.013, 0.500), the pure purple locus extending from thefirst point towards smaller x values, and the spectral locus extendingfrom the third point towards smaller y values can be employed for thefirst light emitting devices 37.

Second Embodiment

The lighting control system according to a second embodiment will beexplained next. The lighting control system according to the secondembodiment differs from the lighting control system according to thefirst embodiment such that a light fixture includes third light emittingdevices, in addition to the first light emitting devices and the thirdlight emitting deices. It also differs from the lighting control systemof the first embodiment such that the emission of the first, second, andthird light emitting devices is controlled in the lighting apparatus.The other aspects are similar to those of the lighting control system ofthe first embodiment. Accordingly, except for FIG. 6, FIG. 8, and FIG.9, the drawings utilized in explaining the first embodiment are alsoapplicable to the second embodiment. The descriptions related to thesedrawings are also similar.

FIG. 14 shows one example of a lighting apparatus 224 and the connectionbetween the lighting apparatus 224 and an external device in thelighting control system 200. FIG. 15 is a diagram of the emission face(the opposite face to the ceiling installation face) of a light fixture230. FIG. 15 shows the light fixture 230 without a cover 33. FIG. 16 isa schematic cross-sectional view of a third light emitting device 237included in the light fixture 230.

As shown in FIG. 14, in the lighting apparatus 224, third light emittingdevices 237 are included as light emitting devices 36 in the lightfixture 230. Furthermore, the emission controller 35 can individuallycontrol the emission by the third emitting devices 237 in addition tothe emission by the first light emitting devices 37 and the emission bythe second light emitting devices 38. For example, the emissioncontroller 35 is able to allow only the first light emitting devices 37or the second light emitting devices 38 to emit light.

Each third light emitting device 237 includes a light emitting element39, a sealing member 43, and a molded part 42. The sealing member 43seals the light emitting element 39 and diffuses the light emitted fromthe light emitting element 39 to be output from the emission face. Thirdlight emitting devices 237 have no wavelength conversion members ascompared to the first light emitting devices 37 and the second lightemitting deices 38. A wavelength conversion member may be employed inplace of the sealing member 43.

The light emitted from a third light emitting device 237 has a peakemission in the range of 360 nm to 400 nm. It can be constructed with,for example, a light emitting element 39 having a peak emission in therange of 360 nm to 400 nm. Furthermore, it is preferable for a thirdlight emitting device 237 to not emit light having 10% or higher of thepeak light intensity in the visible spectrum of 420 nm or higher.

It is preferable for a third light emitting device 237 to not emit lighthaving 10% or higher of the peak light intensity in the wavelength rangeof up to 320 nm. The third light emitting device 237 preferably has apeak emission in the range of 360 nm to 400 nm, and substantiallyeffective emission wavelengths in the 320 nm tot 420 nm range. Thephrase “substantially effective emission” in the present disclosurerefers to light emission having the light intensity of 10% or more ofthe peak light intensity.

In the lighting control system 200, the light emitted from the thirdlight emitting devices 237 is not essentially utilized as illuminationlight. In other words, in a lighting apparatus 224, the white light thatshould be achieved as illumination light, such as incandescent lampcolor, neutral white color, or the like, is achieved without the lightemitted from the third light emitting devices 237. The light emittedfrom the third emitting devices 237, which does not considerably affectcolor toning or dimming, is provided as auxiliary light to address theeffects on the human body.

Accordingly, the number of the third light emitting devices 237 disposedin a lighting apparatus 224 is smaller than the number of the firstlight emitting devices 37 and smaller than the number of the secondlight emitting devices 38. Furthermore, the auxiliary light from thethird light emitting devices 237 output by the lighting apparatus 224has a small illuminance as compared to the illumination light producedby the first light emitting devices 37 and the second light emittingdevices 38.

In a lighting control system 200, the irradiance (W/m²) of the thirdlight emitting devices 237 is controlled in correspondence with thefluctuations of the circadian characteristics of the illumination light.The color toning control mechanism is similar to that explained inrelation to the first embodiment.

For example, in a lighting control system 200, the irradiance (W/m²) ofthe third light emitting devices 237 is controlled in correspondencewith an increase or decrease in the circadian characteristics of theillumination light. For example, the emission of the auxiliary light bythe third light emitting devices 237 is controlled in line with thefluctuations of the circadian characteristics of the illumination lightillustrated in FIGS. 13A to 13E. When the circadian characteristic valueis maximum, the irradiance of light from the third light emittingdevices 237 also becomes maximum, and when the circadian characteristicvalue is minimum, the irradiance of the light from the third lightemitting devices 237 also becomes minimum.

For example, the light emitted from a third light emitting devices 237can be set to have a maximum irradiance of 5.0 W/m². The minimumirradiance can be set as 0.0 W/m², i.e., the third light emittingdevices 237 are off.

Here, the effect of the auxiliary light provided by the third lightemitting devices 237 will be explained. Studies show that exposure to360 to 400 nm wavelength light is effective in suppressing myopiaprogression and reducing depression. It is thus preferable to irradiatethe auxiliary light emitted by the third light emitting devices 237 inthe time period during work hours in which individuals should be workingvigorously. Accordingly, one preferable mode of control is to controlthe light emitted from the third light emitting devices 237 incorrespondence with the circadian characteristics.

Because the 360 nm to 400 nm wavelength range is a part of UVA, exposureto this light for a long time causes human skin to experiencephotodegradation. In the lighting control system 200, the maximumirradiance of the auxiliary light from the third light emitting devices237 is adjusted by taking this into consideration. Considering the factthat the UVA irradiance in the noon-hour in the middle of summer inKanagawa Prefecture, Japan is about 50 W/m², for example, the upperlimit of the irradiance is preferably set to about ⅕ to about 1/10 ofthis, i.e., 10 W/m² at most, in the lighting control system 200.

Furthermore, the lighting control system 200 may be adapted to set theupper limit for the duration of the auxiliary light emission by thethird light emitting devices 237 so as not to allow the emission tocontinue beyond the maximum duration. For example, the dimmingcontroller 61 restricts (stops) the auxiliary light emission for acertain period of time once the continuous emission of the auxiliarylight reaches the maximum duration before resuming the emission past thetime period. As a specific example, the upper limit for the duration canbe set to one and a half hours, and the duration of restriction can beset to 30 minutes, which begins when reaching the upper limit.

Avoiding prolonged irradiation can reduce photodegradation. If the firstlight emitting devices 37 and the second light emitting devices 38 weresuddenly turned off, i.e., illumination light is turned off, during workhours, business operations would be hindered. However, the light fixture230 can remain functional, not hindering business operations, even ifthe third light emitting devices 237 are turned off.

The lighting control system 200 that controls the third light emittingdevices 237 in correspondence with circadian characteristics describedabove is considered particularly effective in the case of constructing alight fixture 230 with first light emitting devices 37 and second lightemitting devices 38 that emit light of the same correlated colortemperature. As is understood from the comparison between Table 1 andTable 2 presented in relation to the first embodiment, the amount ofchange in the circadian characteristic values (the difference betweenthe maximum and the minimum values) is smaller in the cases where thelight emitting devices having employed for both the first and secondlight emitting devices emit light of the same correlated colortemperature as compared to the cases where the light emitting devicesthat emit light of different correlated color temperatures are employed.Accordingly, utilizing auxiliary light in addition to illumination lightcan invigorate individuals during an appropriate period of time.

Alternatively, for example, a lighting control system 200 can controlthe irradiance (W/m²) of the third light emitting devices 237 incontrary to an increase or decrease in the circadian characteristics. Inother words, the auxiliary light emitted by the third light emittingdevices 237 is controlled to fluctuate in the opposite direction of thefluctuations in the circadian characteristics of the illumination lightillustrated in FIG. 13A to FIG. 13E. When the circadian characteristicvalue is maximum, the irradiance of the third light emitting devices 237becomes minimum, and when the circadian characteristic value is minimum,the irradiance of the third light emitting devices 237 becomes maximum.

The lighting control system 200 that controls the third light emittingdevices 237 in contrary to the circadian characteristics described aboveis considered effective, for example, when controlling lighting by usingthe first light emitting devices 37 and the second light emittingdevices 38 that emit light having different correlated colortemperatures in a facility such as a hospital. As is understood fromTable 2 presented in relation to the first embodiment, in the caseswhere the light emitting devices of different color temperatures areused for the first and second light emitting devices, the circadiancharacteristic values also decrease as the correlated color temperaturesdecrease. In a hospital room for treating depression patients or thelike, for example, there may be a need to reduce the risk of allowingthe effect of suppressing invigoration caused by a decline in thecircadian characteristics to make a patient feel depressed. Accordingly,irradiating the auxiliary light during the time period of reducedcircadian characteristics can promote the patient's mental stabilitywhile regulating his/her circadian rhythm.

Variations of Second Embodiment

In the lighting control system 200 of the second embodiment, the thirdlight emitting devices 237 were described as those emitting auxiliarylight having a peak emission in the 360 nm to 400 nm range, but theauxiliary light is not limited to this. The third light emitting devices237 explained in relation to the second embodiment may include a lightemitting device that emits light having a peak emission outside of therange of 360 nm to 750 nm in addition to those emitting auxiliary lighthaving a peak emission in the 360 nm to 400 nm range.

For example, auxiliary light having a peak emission in the range of 295nm to 315 nm that promotes vitamin D generation may be irradiated.However, the light of this wavelength range, which is a part of UVB, hasa greater photodegradation impact than UVA. Accordingly, it ispreferable to set the maximum irradiance of this light to be lower thanthat of the auxiliary light having a peak emission in the range of 360nm to 400 nm.

For the third light emitting devices 237 in the lighting control system200, those emitting auxiliary light having a peak emission in the 295 nmto 315 nm range, for example, may be employed in place of those emittingauxiliary light having a peak emission in the 360 nm to 400 nm range.For the auxiliary light, one having a peak emission in the wavelengthrange of up to 400 nm or at least 750 nm, and a light intensity of up to10% of the peak light intensity in the 420 nm to 730 nm wavelength rangecan be employed. By controlling the irradiance, the auxiliary light canaffect human internal rhythms and mental state.

Although each embodiment of the present invention has been explainedabove, the technical ideas of the present invention are not limited tothose specifically described above. For example, in any embodiment, theinstallation location of the lighting control system related to thepresent invention is not limited to an office building. The lightingcontrol system may be built, for example, in a hospital, factory,school, or commercial facility.

The characteristics related to circadian rhythms do not have to belimited to those explained in relation to the embodiments. For example,in the embodiments, MR using the circadian response curve having a peaknear 480 nm to 490 nm in FIG. 1 was used for the circadiancharacteristic 1, but the circadian characteristic values calculated byusing the action spectrum for melatonin secretion suppression having apeak near 464 nm prepared by Professor Brainard in place of thecircadian response curve may be employed.

Furthermore, in the examples explained above, a light fixture isconstructed with first light emitting devices 37 and second lightemitting devices 38 that are formed as individual light emitting devices36, but a first light emitting device 37 and a second light emittingdevice 38 may be combined in a single light emitting device.

FIG. 17A to FIG. 17C show some examples of light fixture forms thatinclude a first light emitting device 37 and a second light emittingdevice 38 formed in the casing of a single light emitting device 36. Inany of these cases, the first light emitting device 37 and the secondlight emitting device 38 share a single molded part 42.

FIG. 17A shows a form of the light emitting device 36 having twocavities provided by a single molded part 42 where a light emittingelement 39 of the first light emitting device 37 and a wavelengthconversion member 40, and a light emitting element 39 for the secondlight emitting device 38 and a wavelength conversion member 40 areseparately disposed in the cavities.

FIG. 17B shows a form of the light emitting device 36 having a singlecavity provided by a single molded part 42 where a light emittingelement 39 of the first light emitting device 37 and wavelengthconversion members 40 thereon, a light emitting element 39 for thesecond light emitting device 38 and wavelength conversion members 40thereon are disposed in the cavity.

The wavelength conversion member 40 for the light emitted from the firstlight emitting device 37 that is unnecessary for the light emitted fromthe second light emitting device 38 is disposed only on the lightemitting element 39 of the first light emitting device 37. Similarly,the wavelength conversion member 40 for the light emitted from thesecond light emitting device 38 that is unnecessary for the lightemitted from the first light emitting device 37 is disposed only on thelight emitting element 39 of the second light emitting device 38. Thewavelength conversion member 40 that is needed for the light emittedfrom both the first light emitting device 37 and the second lightemitting device 38 is disposed to cover the first light emitting device37 and the second light emitting device 38.

FIG. 17C shows a form of the light emitting device 36 having a singlecavity provided by a single molded part 42 where a light emittingelement 39 of the first light emitting device 37, a light emittingelement 39 for the second light emitting device 38 and wavelengthconversion members 40 thereon are disposed in the cavity.

In comparison to FIG. 17B, there is no wavelength conversion member 40for the light emitted from the first light emitting device 37. Thewavelength conversion member 40 for the light emitted from the secondlight emitting device 38 that is unnecessary for the light emitted fromthe first light emitting device 37 is disposed only on the lightemitting element of the second light emitting device 38.

The wavelength conversion member 40 disposed only on the light emittingelement 39 of the second light emitting device 38 is multilayered. Thismay be a single layer. In each layer, phosphors are localized near thelower face. For example, adhering a phosphor sheet to a glass materialcan form such a wavelength conversion member 40.

The lateral faces of the light emitting element 39 of the second lightemitting device 38 are covered by a reflecting layer 44. This allows thelight from the light emitting element 39 of the first light emittingdevice 37 to be reflected by the reflecting layer 44 without enteringthe light emitting element 39 of the second light emitting device 38.Accordingly, this can restrain the light emitted from the light emittingelement 39 of the first light emitting device 37 from being converted bythe wavelength conversion member 40 disposed only on the light emittingelement 39 of the second light emitting device 38.

The present invention is applicable to a device even if the device doesnot include all of the constituent elements of the device disclosed inthe embodiments described above. Even in the event that a certainconstituent element of a device is not recited in a claim, the presentinvention is applicable so long as the device falls within the scope ofdesign flexibility for a person of ordinary skill in the art. Thepresent invention is disclosed based on this premise.

The lighting control systems or the light fixtures disclosed in theembodiments can be used in lighting systems installed in an indoor spaceor the like.

What is claimed is:
 1. A lighting control system comprising: a lightfixture comprising: a first light emitting device configured to emitlight having a correlated color temperature in the range of ±100 K froma prescribed value, a second light emitting device configured to emitlight having a correlated color temperature in the range of ±100 K fromthe prescribed value, and an emission controller configured to cause thelight fixture to irradiate illumination light by controlling irradiationpercentages of the light emitted from the first light emitting deviceand the light emitted from the second light emitting device; and aninformation processing apparatus communicably connected to the lightfixture, the information processing apparatus comprising a dimmingcontroller configured to change the irradiation percentages of the lightemitted from the first light emitting device and the light emitted fromthe second light emitting device of the light fixture in accordance witha time of day by transmitting dimming instructions; wherein the emissioncontroller is configured to control the irradiation percentages of thelight emitted from the first light emitting device and the light emittedfrom the second light emitting device based on the dimming instructionssuch that a difference between a maximum melanopic ratio of theillumination light and a minimum melanopic ratio of the illuminationlight is 0.01 or higher in a time period during which the illuminationlight is irradiated.
 2. The lighting control system according to claim1, wherein: the time period is a time period during which theillumination light of at least a certain illuminance is irradiated inaccordance with a work environment.
 3. The lighting control systemaccording to claim 1, wherein: the time period during which theillumination light is irradiated encompasses at least 10:00 and 17:00,and the dimming controller is configured to transmit the dimminginstructions such that the melanopic ratio of the illumination light at10:00 is larger than the melanopic ratio of the illumination light at17:00.
 4. The lighting control system according to claim 1, wherein: theemission controller is configured to control the irradiation percentagesof the light emitted from the first light emitting device and the lightemitted from the second light emitting device based on the dimminginstructions such that the difference between the maximum melanopicratio of the illumination light and the minimum melanopic ratio of theillumination light during a timer period from 08:00 to 12:00 is smallerthan the difference between the maximum melanopic ratio of theillumination light and the minimum melanopic ratio of the illuminationlight during a time period from 14:00 to 18:00.
 5. The lighting controlsystem according to claim 1, wherein: the light fixture furthercomprises a third light emitting device configured to emit light havinga peak emission in a range of 360 nm to 400 nm; the emission controlleris further configured to control an irradiance of the light emitted fromthe third light emitting device; and the dimming controller is furtherconfigured to transmit dimming instructions to change the irradiance ofthe light emitted from the third light emitting device in correspondencewith fluctuations in the melanopic ratio of illumination light producedby the first light emitting device and the second light emitting device.6. The lighting control system according to claim 5, wherein theemission controller is configured to control the irradiance of the lightemitted from the third light emitting device based on the dimminginstructions such that the irradiance of the light emitted from thethird light emitting device fluctuates in line with the fluctuations inthe melanopic ratio of the illumination light produced by the firstlight emitting device and the second light emitting device.
 7. Thelighting control system according to claim 5, wherein the emissioncontroller is configured to control the irradiance of the light emittedfrom the third light emitting device based on the dimming instructionsso as not to allow the third light emitting device to continue emittinglight past a predetermined duration.
 8. A lighting control systemcomprising: a light fixture comprising: a first light emitting deviceconfigured to emit light having a correlated color temperature, a secondlight emitting device configured to emit light having a correlated colortemperature different from that of the light emitted from the firstlight emitting device, and an emission controller configured to causethe light fixture to irradiate illumination light by controllingirradiation percentages of the light emitted from the first lightemitting device and the light emitted from the second light emittingdevice; and an information processing apparatus communicably connectedto the light fixture, the information processing apparatus comprising adimming controller configured to change the irradiation percentages ofthe light emitted from the first light emitting device and the lightemitted from the second light emitting device of the light fixture inaccordance with a time of day by transmitting dimming instructions;wherein the first light emitting device is configured to emit the lightin the region of a CIE1931 color space chromaticity diagram defined by afirst straight line connecting a first point whose x, y coordinates are(0.280, 0.070) and a second point whose x, y coordinates are (0.280,0.500), a second straight line connecting the second point and a thirdpoint whose x, y coordinates are (0.013, 0.500), a pure purple locusextending from the first point towards smaller x values, and a spectrallocus extending from the third point towards smaller y values; andwherein the emission controller is configured to control the irradiationpercentages of the light emitted from the first light emitting deviceand the light emitted from the second light emitting device based on thedimming instructions such that, at least in a correlated colortemperature range of 3000K to 5000K, a difference between a maximummelanopic ratio of the illumination light and a minimum melanopic ratioof the illumination light is 0.40 or higher in a time period duringwhich the illumination light is irradiated.
 9. The lighting controlsystem according to claim 8, wherein the second light emitting device isconfigured to emit light having a correlated color temperature in arange of 1500K to 3000K in the CIE1931 color space chromaticity diagram.10. The lighting control system according to claim 8, wherein: the lightfixture further comprises a third light emitting device configured toemit light having a peak emission in a range of 360 nm to 400 nm; theemission controller is further configured to control an irradiance ofthe light emitted from the third light emitting device; and the dimmingcontroller is further configured to transmit dimming instructions tochange the irradiance of the light emitted from the third light emittingdevice in correspondence with fluctuations in the melanopic ratio ofillumination light produced by the first light emitting device and thesecond light emitting device.
 11. The lighting control system accordingto claim 10, wherein the emission controller is configured to controlthe irradiance of the light emitted from the third light emitting devicebased on the dimming instructions such that the irradiance of the lightemitted from the third light emitting device fluctuates in contrary tothe fluctuations in the melanopic ratio of the illumination lightproduced by the first light emitting device and the second lightemitting device.
 12. The lighting control system according to claim 10,wherein the emission controller is configured to control the irradianceof the light emitted from the third light emitting device based on thedimming instructions so as not to allow the third light emitting deviceto continue emitting light past a predetermined duration.
 13. A lightingcontrol system comprising: a light fixture comprising: a first lightemitting device configured to emit light having a correlated colortemperature, a second light emitting device configured to emit lighthaving a correlated color temperature different from that of the lightemitted from the first light emitting device, and an emission controllerconfigured to cause the light fixture to irradiate illumination light bycontrolling irradiation percentages of the light emitted from the firstlight emitting device and the light emitted from the second lightemitting device; and an information processing apparatus communicablyconnected to the light fixture, the information processing apparatuscomprising a dimming controller configured to change the irradiationpercentages of the light emitted from the first light emitting deviceand the light emitted from the second light emitting device of the lightfixture in accordance with a time of day by transmitting dimminginstructions; wherein the first light emitting device is configured toemit light in a region of a CIE1931 color space chromaticity diagramdefined by a first straight line connecting a first point whose x, ycoordinates are (0.280, 0.070) and a second point whose x, y coordinatesare (0.280, 0.500), a second straight line connecting the second pointand a third point whose x, y coordinates are (0.013, 0.500), a purepurple locus extending from the first point towards smaller x values,and a spectral locus extending from the third point towards smaller yvalues; and wherein the emission controller is configured to control theirradiation percentages of the light emitted from the first lightemitting device and the light emitted from the second light emittingdevice based on the dimming instructions such that, at least in acorrelated color temperature range of 2700K to 6500K, a differencebetween a maximum melanopic ratio of the illumination light and aminimum melanopic ratio of the illumination light is 0.65 or higher in atime period during which the illumination light is irradiated.
 14. Thelighting control system according to claim 13, wherein the second lightemitting device is configured to emit light having a correlated colortemperature in a range of 1500K to 2700K in the CIE1931 color spacechromaticity diagram.
 15. The lighting control system according to claim13, wherein the light fixture further comprises a third light emittingdevice configured to emit light having a peak emission in a range of 360nm to 400 nm; the emission controller is further configured to controlan irradiance of the light emitted from the third light emitting device;and the dimming controller is further configured to transmit dimminginstructions to change the irradiance of the light emitted from thethird light emitting device in correspondence with fluctuations in themelanopic ratio of illumination light produced by the first lightemitting device and the second light emitting device.
 16. The lightingcontrol system according to claim 15, wherein the emission controller isconfigured to control the irradiance of the light emitted from the thirdlight emitting device based on the dimming instructions such that theirradiance of the light emitted from the third light emitting devicefluctuates in contrary to the fluctuations in the melanopic ratio of theillumination light produced by the first light emitting device and thesecond light emitting device.
 17. The lighting control system accordingto claim 15, wherein the emission controller is configured to controlthe irradiance of the light emitted from the third light emitting devicebased on the dimming instructions so as not to allow the third lightemitting device to continue emitting light past a predeterminedduration.